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Thread: Shutting off engine at red lights?

  1. #11
    Administrator MetroMPG's Avatar
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    The light for the cross traffic warns when your light is going to change back to green.

    In cars with automatic stop/start, the fuel saving is roughly 5 to 10% on the city fuel economy cycle.


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        click to view fuel log View my fuel log 2015 Micra S manual: 5.0 L/100 km ... 56.5 mpg (Imp) ... 20.0 km/L ... 47.0 mpg (US) ...


  2. #12
    Senior Member dani3d's Avatar
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    it's just not worth it for me because my fuel economy was worse when doing it often. I can beleive there is a fuel economy on the longest lights, like 1 minute at least, but for anything less then 1 minute it was costing me more to stop and start than to just let it idle.

    I still do it at the longest lights only.

    Quote Originally Posted by MetroMPG View Post
    The light for the cross traffic warns when your light is going to change back to green.

    In cars with automatic stop/start, the fuel saving is roughly 5 to 10% on the city fuel economy cycle.

        __________________________________________

        click to view fuel log View my fuel log 2015 Micra SR automatic: 7.0 L/100 km ... 40.4 mpg (Imp) ... 14.3 km/L ... 33.6 mpg (US) ...


  3. #13
    Administrator Daox's Avatar
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    My guess is that your fuel savings from turning the engine off was lost in the normal variation of tank to tank mileage. I'm not sure if the dash reads MPG right with the engine off. A scangauge or similar device would track it more accurately for your trips and would give you a better idea of your savings.

    Modern day fuel injected engines, especially once warmed up, requires virtually no fuel enrichment to start back up, thus no fuel is 'wasted' by starting. If you don't waste any fuel starting, then any time spent idling will decrease your fuel economy. The gains may be small if you don't get stuck at many lights, and thats a very good thing. But, if you do get stuck at a lot of lights you can definitely see gains by using this technique. If there weren't gains to be made, OEMs would not be equipping vehicles with start/stop systems from the factory.

  4. #14
    Senior Member dani3d's Avatar
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    wrong guessing, because I do the same exact routine week after week, so I can precisely compare and I tried for 2 different weeks doing the same routine with the same results. It's just not worth it with my car.

    And wrong about the better idea of my savings, because I am measuring my fuel economy with actual mileage and number of litter via the fuelly.com application, so this does not lie. The car computer was in deed showing fuel economy but it was not reflected in real life with real calculation. In fact it was more expensive in gaz both times I tried it. If it's less then one minute, it's just not worth it.

    Why don't you try it yourself and see if your modern day fuel injected engine does perform the way you expect?

    I can assure you that my car does waste fuel by starting. And you cannot compare an engine that has been designed for start and stop with one that was not. I can only go by the results I got and the mileage I did and the number of liters to do it.

    In winter, that would be much worse and starting a cold engine is not eco friendly and it takes a lot of time to warm up at -25C.

    I tried it for 1 week by shutting down at each light and that was awfull, about .6 more fuel consomption. I tried 1 week with most lights and that was just slightly better. Best I get for now is to only do it at very long lights and even so, ther verdict is still not sure on that yet.
    Last edited by dani3d; 08-26-2015 at 08:15 PM.

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        click to view fuel log View my fuel log 2015 Micra SR automatic: 7.0 L/100 km ... 40.4 mpg (Imp) ... 14.3 km/L ... 33.6 mpg (US) ...


  5. #15
    Senior Member Howie's Avatar
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    Not to mention extra wear and tear on the starter.

        __________________________________________

        click to view fuel log View my fuel log 2015 Micra S automatic: 7.9 L/100 km ... 35.7 mpg (Imp) ... 12.6 km/L ... 29.7 mpg (US) ...


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  7. #16
    Senior Member dani3d's Avatar
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    Yes that too, and it's quite significant. In cars that are designed for stop and start, they have a better starter which is heavy duty and meant for this. I suspect our starters would not last long if doing it every day.

        __________________________________________

        click to view fuel log View my fuel log 2015 Micra SR automatic: 7.0 L/100 km ... 40.4 mpg (Imp) ... 14.3 km/L ... 33.6 mpg (US) ...


  8. #17
    Administrator Daox's Avatar
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    I do kill my engine quite a bit while I drive. Its a technique called pulse and glide. In my 99 Chevy Metro this nets me fuel efficiency of around 3.9l/100km in the summer.

  9. #18
    Senior Member dani3d's Avatar
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    glide? People behind you must be very anoyed if you keep accelerating and decelarating all the time. Not to mention the higher risk of having a ticket if going over the limit. Have you tried shutting off your engine at traffic lights?
    Last edited by dani3d; 08-27-2015 at 08:36 PM.

        __________________________________________

        click to view fuel log View my fuel log 2015 Micra SR automatic: 7.0 L/100 km ... 40.4 mpg (Imp) ... 14.3 km/L ... 33.6 mpg (US) ...


  10. #19
    Administrator Daox's Avatar
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    Yes, I do turn my engine off at lights. Actually, my engine is off before I get to the light. I see no point in running the engine if I'm headed towards a red light. If it turns green on the way, I start the car up and go. If I must stop, I wait and when it turns green (or is about to turn green if I can see the cross light) I start up and go.

    As for the pulse and glide, it is used in appropriate situations and traffic patterns. For instance, in light traffic I use hills when using pulse and glide to maintain a more normal speed (pulse up, coast down). I don't typically do it in heavy traffic if its only a single lane road so as not to annoy other drivers. Typically, there is not much more speed variation than anyone else, and certainly less than someone on a cell phone.

    I also rarely exceed the speed limit. I'd say more people are annoyed by me actually driving the speed limit than any variation in speed they may notice. To that I say tough. Its the law and I do try to obey it. I'm certainly not going to disobey it just because someone else thinks I should. They certainly won't be paying my ticket if I am caught.

    No doubt this is an odd driving technique to most out there. It is also pretty advanced in the slew of fuel economy driving techniques that are used to get better fuel economy. That being said its also highly effective, and if you're really wanting good mileage its worth looking into.

  11. #20
    Senior Member micrapolis's Avatar
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    that....is pretty dangerous. im not sure it's even legal.



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